Columns in partially restrained construction: analytical studies

Abstract

The American Institute of Steel Construction Proposed Load and Resistance Factor Design Specification recognizes the ability of connections that function as less than fully rigid to transmit limited moments and to provide some measure of end restraint to columns in its definition of partially restrained (PR) construction. An analytical procedure for determining the response up to collapse of subassemblages in which semirigid beam-to-column connections are present is derived. This employs a nonlinear finite element column analysis together with analytical representation of experimentally determined connection moment–rotation [Formula: see text] curves. To trace the full response under any load path produced by a combination of beam loads and direct column load, it is necessary to allow for possible reversal in the direction of rotation of any of the connections. The program is used to study the effect of different connection types (ranging from very flexible web cleats to almost rigid extended end plates) and different load paths on column behaviour in nonsway subassemblages. It is found that the degree of rotation required from each connection is an important parameter in determining column response. Key words: buckling, columns, connections, frames, stability, steel, structural design, structures.